Delphi hour:minutes input in a tEdit - delphi

Question

I'm out of ideas so I appeal to the immense StackOverflow supermind. What I want is to have a a tedit or whatever text control that lets me input text with the following format: "nnnnnn:nn" where n is an integer. Examples: If I type "100" I want a "100:00" text property. If I type "123:1" I should get "123:01". May be I should only type numbers in a calculator style with the ":" separator at a fixed position. I want rejected something like this "10 : 1", "10:95" (minutes 0-59), "0100:10", etc. Any ideas or component?
Greetings, Marcelo.

Answer 1

Any formatting that changes in input text during entry is bad, so the following shows you how to do it, but input is only changed on exiting the field or pressing the enter key:
Edit 1 is the edit field in question. Edit2 is simply there to allow the tab key to exit Edit1.
Note that I am using standard evets and event name (OnKeyPress and OnExit)
unit Unit10;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, System.StrUtils, Vcl.Mask;
type
TForm10 = class(TForm)
Edit1: TEdit;
Edit2: TEdit;
procedure Edit1KeyPress(Sender: TObject; var Key: Char);
procedure Edit1Exit(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
function EntryValid( const pVal : string ) : boolean;
end;
var
Form10: TForm10;
implementation
{$R *.dfm}
{ TComboBox }
procedure TForm10.Edit1Exit(Sender: TObject);
var
iPos : integer;
iCheck : string;
i1 : string;
begin
iPos := Pos( ':', Edit1.Text );
if iPos > 0 then
begin
// we already know there can only be one ':'
i1 := Copy( Edit1.Text, 1, iPos );
iCheck := Copy(Edit1.Text, iPos + 1 );
if iCheck = '' then
begin
Edit1.Text := i1 + '00';
end
else if StrToInt( iCheck ) < 10 then
begin
Edit1.Text := i1 + '0' + iCheck;
end
else
begin
// already correct, so ignore
end;
end
else
begin
Edit1.Text := Edit1.Text + ':00';
end;
end;
procedure TForm10.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
// only allow numbers and a single :
case Key of
'0'..'9': ;
':':
begin
if Pos( ':', Edit1.Text ) <> 0 then
begin
Key := #0; // don't allow
Beep;
end;
end;
#13:
begin
Key := #0; // silently this time
Edit1Exit( Sender );
end
else
begin
Key := #0;
Beep;
end;
end;
end;
function TForm10.EntryValid(const pVal: string): boolean;
var
iPos : integer;
iCheck : string;
begin
iPos := Pos( ':', pVal );
if iPos > 0 then
begin
// we already know there can only be one ':'
iCheck := Copy( pVal, iPos + 1 );
if iCheck = '' then
begin
Result := TRUE;
end
else if StrToIntDef( iCheck, 60 ) < 60 then
begin
Result := TRUE;
end
else
begin
Result := FALSE;
end;
end
else
begin
Result := TRUE;
end;
end;
end.